How to change the image in the logo using a custom theme in Totara?

Let us suppose, in Totara we have a custom theme named “test”. Now, we will discuss how will we display a custom logo on our website. There are three steps to change your site logo:

1. Firstly, you will have to override the standard site_logo() function into your theme. To do this, create a function render_site_logo() in the “test/classes/renderer.php” file as:
   public function render_site_logo() {
global $OUTPUT, $CFG, $SITE;
$templatecontext = array(
'siteurl' => $CFG->wwwroot . '/',
'shortname' => $SITE->shortname
);
$templatecontext['logourl'] = $OUTPUT->pix_url('logo_copy', ‘’); //”logo_copy.png” should be existed in “pix” folder of your theme
$templatecontext['logoalt'] = ‘<logoalt_string>’;
return $this->render_from_template('test/site_logo',
$templatecontext); //it will call the site_logo.mustache file
}
2. Now, Create a new file named “site_logo.mustache” into the “templates” folder and paste the below contents into that file.
   <h1 id="logo" class="site-logo">
<a class="navbar-brand" href="{{siteurl}}">
{{#logourl}}<img class="logo img-responsive" src="{{logourl}}" {{#logoalt}}alt="{{.}}"{{/logoalt}} />{{/logourl}}
{{^logourl}} {{/logourl}}
<span class="sr-only">{{shortname}}</span>
</a>
</h1>
3. Now, call this custom logo in the header layout of your Totara custom theme. Place the below code in the appropriate location into the “test/layout/partials/header.php” file.
   <div class="navbar-header pull-left">
render_site_logo(); ?>